Spatial stream configuration encoding for wifi

ABSTRACT

A first client station receives a multi-user physical layer (PHY) data unit from an access point. The multi-user PHY data unit includes i) a PHY preamble, and ii) a multi-user multiple input, multiple output (MU-MIMO) transmission. The PHY preamble includes a subfield that indicates respective numbers of spatial streams allocated to respective client stations among a plurality of client station that includes the first client station. The subfield has been encoded according to an encoding that supports allocating up to sixteen spatial streams to up to eight intended receivers, and the subfield consists of six or fewer bits. The first client station decodes the subfield to determine a number of spatial streams allocated to the first client station and processes the determined number of spatial streams in the MU-MIMO transmission.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation application of U.S.application Ser. No. 16/889,769, filed on Jun. 1, 2020, entitled“SPATIAL STREAM CONFIGURATION ENCODING FOR WIFI,” which claims thebenefit of U.S. Provisional Patent Application No. 62/854,802, entitled“Spatial Configuration Subfield Encoding Format (HE-SIGB Preamble UserField),” filed on May 30, 2019. Both of the applications referencedabove are hereby incorporated by reference herein their entireties.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems, and more particularly to multi-user transmissions usingmultiple spatial streams in a wireless local area network (WLAN).

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pasttwo decades, and development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11 Standard family hasimproved single-user peak data rates. One way in which data rates havebeen increased is by simultaneously transmitting independent datastreams via different spatial streams. For example, the IEEE 802.11axStandard permits simultaneous transmissions via up to eight spatialstreams to up to eight client stations. Work has now begun on a newiteration of the IEEE 802.11 Standard, which is referred to as the IEEE802.11be Standard, or Extremely High Throughput (EHT) WLAN. The IEEE802.11be Standard may permit simultaneous transmissions via up tosixteen (or perhaps even more) spatial streams to up to eight (orperhaps even more) client stations.

SUMMARY

In an embodiment, a method is for communicating in a wireless local areanetwork (WLAN) that utilizes multi-user multiple input, multiple output(MU-MIMO). The method includes: receiving, at a first client station, amulti-user physical layer (PHY) data unit from an access point, themulti-user PHY data unit including i) a PHY preamble, and ii) an MU-MIMOtransmission, wherein the PHY preamble includes a subfield thatindicates respective numbers of spatial streams allocated to respectiveclient stations among a plurality of client station that includes thefirst client station, wherein the subfield has been encoded according toan encoding that supports allocating up to sixteen spatial streams to upto eight intended receivers, wherein the encoding corresponds to a tablehaving table elements that indicate respective allocated numbers ofspatial streams, wherein respective values of the subfield correspondsto respective rows of the table, and wherein respective columns of thetable correspond to the respective client stations, and wherein thesubfield is generated to consist of six or fewer bits; decoding, at thefirst client station, the subfield to determine a number of spatialstreams allocated to the first client station; and processing, by thefirst client station, the determined number of spatial streams in theMU-MIMO transmission.

In another embodiment, a first communication device comprises a wirelessnetwork interface device that is configured to communicate in a WLANusing MU-MIMO. The wireless network interface device comprises one ormore integrated circuit (IC) devices configured to: receive a multi-userphysical layer (PHY) data unit from an access point, the multi-user PHYdata unit including i) a PHY preamble, and ii) an MU-MIMO transmission,wherein the PHY preamble includes a subfield that indicates respectivenumbers of spatial streams allocated to respective client stations amonga plurality of client station that includes the first client station,wherein the subfield has been encoded according to an encoding thatsupports allocating up to sixteen spatial streams to up to eightintended receivers, wherein the encoding corresponds to a table havingtable elements that indicate respective allocated numbers of spatialstreams, wherein respective values of the subfield corresponds torespective rows of the table, and wherein respective columns of thetable correspond to the respective client stations, and wherein thesubfield is generated to consist of six or fewer bits. The one or moreIC devices are further configured to: decode, the subfield to determinea number of spatial streams allocated to the first client station andprocess the determined number of spatial streams in the MU-MIMOtransmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example communication system in which anaccess point (AP) can simultaneously transmit via up to sixteen spatialstreams to up to eight client stations in a downlink (DL) multi-user(MU) physical layer (PHY) data unit or packet using multiple input,multiple output (MU-MIMO) techniques, according to an embodiment.

FIG. 2 is a diagram of an example portion of a PHY preamble included ina DL MU packet transmitted in the communication system of FIG. 1 ,according to an embodiment.

FIG. 3 is a flow diagram of an example method for communicating in aWLAN that utilizes MU-MIMO, according to an embodiment.

FIG. 4 is a flow diagram of another example method for communicating ina WLAN that utilizes MU-MIMO, according to another embodiment.

DETAILED DESCRIPTION

The IEEE 802.11ax Standard permits an access point (AP) tosimultaneously transmit via up to eight spatial streams to up to eightclient stations in a downlink (DL) multi-user (MU) physical layer (PHY)data unit or packet using multiple input, multiple output (MU-MIMO)techniques. The DL MU packet may use MU-MIMO for all intended stations,or the DL MU packet may use a combination of orthogonal frequencydivision multiple access (OFDMA) and MU-MIMO, where MU-MIMO is only usedin certain frequency segments or resource units (RUs). To inform clientstations of how many spatial streams are allocated client stations in aDL MU packet, the DL MU packet includes, in a PHY preamble of thepacket, spatial configuration subfields that indicate the spatialstreams allocated to respective client stations that are receiving anMU-MIMO transmission. In particular, a respective spatial configurationsubfield is included for each client station that is an intendedreceiver of an MU-MIMO transmission in the DL MU packet. The clientstation uses the spatial configuration subfield corresponding to theclient station, along with other information in the PHY preamble, todetermine how many spatial streams in DL MU packet have been allocatedto the client station.

According to the IEEE 802.11ax Standard, each spatial configurationsubfield consists of four bits, which is sufficient for indicatingallocations of up to eight spatial streams to up to eight clientstations.

A next generation wireless local area network (WLAN) protocol (e.g., theIEEE 802.11be Standard, sometimes referred to as the Extremely HighThroughput (EHT) WLAN Standard) may permit simultaneous transmissionsvia up to sixteen (or perhaps even more) spatial streams to up to eight(or perhaps even more) client stations. The spatial configurationsubfield of the IEEE 802.11ax Standard cannot be used for indicatingallocations of up to sixteen spatial streams to up to eight clientstations.

In various embodiments described below, example encodings of a spatialconfiguration subfield for a DL MU packet are described. The exampleencodings of the spatial configuration subfield are suitable forindicating allocations for the DL MU packet of up to sixteen spatialstreams to up to eight client stations. In one embodiment, a respectivespatial configuration subfield is included for each client station thatis an intended receiver of an MU-MIMO transmission within the DL MUpacket, and each spatial configuration subfield consists of six bits.

In other embodiments, example encodings of a spatial configurationsubfield permit a spatial configuration subfield that consists of fivebits or four bits to reduce transmission overhead for the DL MU packet.For instance, in one embodiment, a respective spatial configurationsubfield is included for each client station that is an intendedreceiver of an MU-MIMO transmission within the DL MU packet, and eachspatial configuration subfield consists of five bits. In anotherembodiment, a respective spatial configuration subfield is included foreach client station that is an intended receiver of an MU-MIMOtransmission within the DL MU packet, and each spatial configurationsubfield consists of four bits.

FIG. 1 is a diagram of an example WLAN 110 that uses DL MU packets thatemploy MU-MIMO, according to an embodiment. The WLAN 110 includes an AP114 that comprises a host processor 118 coupled to a wireless networkinterface device 122. The wireless network interface device 122 includesone or more medium access control (MAC) processors 126 (sometimesreferred to herein as “the MAC processor 126” for brevity) and one ormore PHY processors 130 (sometimes referred to herein as “the PHYprocessor 130” for brevity). The PHY processor 130 includes a pluralityof transceivers 134, and the transceivers 134 are coupled to a pluralityof antennas 138. Although three transceivers 134 and three antennas 138are illustrated in FIG. 1 , the AP 114 comprises at least sixteenantennas 138 to support transmission of up to 16 spatial streams, asbeing considered for the IEEE 802.11be Standard, according to anembodiment. the AP 114 includes other suitable numbers of transceivers134 and antennas 138 in other embodiments. In some embodiments, the AP114 includes a higher number of antennas 138 than transceivers 134, andantenna switching techniques are utilized.

In an embodiment, the wireless network interface device 122 isconfigured for operation within a single RF band at a given time. In anembodiment, the wireless network interface device 122 is configured tosimultaneously communicate via multiple communication links inrespective frequency segments within a single RF band, and/or tocommunicate via the multiple communication links at different times. Inanother embodiment, the wireless network interface device 122 isadditionally configured for operation within two or more RF bands at thesame time or at different times. For instance, in an embodiment, thewireless network interface device 122 is configured to the wirelessnetwork interface device 122 is configured to simultaneously communicatevia multiple communication links in respective RF bands, and/or tocommunicate via the multiple communication links at different times. Inan embodiment, the wireless network interface device 122 includesmultiple PHY processors 130, where respective PHY processors 130correspond to respective RF bands. In another embodiment, the wirelessnetwork interface device 122 includes a single PHY processor 130, whereeach transceiver 134 includes respective RF radios corresponding torespective RF bands.

The wireless network interface device 122 is implemented using one ormore integrated circuits (ICs) configured to operate as discussed below.For example, the MAC processor 126 may be implemented, at leastpartially, on a first IC, and the PHY processor 130 may be implemented,at least partially, on a second IC. The first IC and the second IC maybe packaged together in a single IC package thereby forming a modulardevice, or the first IC and the second IC may be coupled together on asingle printed circuit board (PCB), for example, or another suitablesubstrate, in various embodiments. As another example, at least aportion of the MAC processor 126 and at least a portion of the PHYprocessor 130 may be implemented on a single IC. For instance, thewireless network interface device 122 may be implemented using a systemon a chip (SoC), where the SoC includes at least a portion of the MACprocessor 126 and at least a portion of the PHY processor 130.

In an embodiment, the host processor 118 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a random access memory (RAM), a read-only memory (ROM), aflash memory, etc. In an embodiment, the host processor 118 may beimplemented, at least partially, on a first IC, and the network device122 may be implemented, at least partially, on a second IC. As anotherexample, the host processor 118 and at least a portion of the wirelessnetwork interface device 122 may be implemented on a single IC.

In various embodiments, the MAC processor 126 and/or the PHY processor130 of the AP 114 are configured to generate data units, and processreceived data units, that conform to a WLAN communication protocol suchas a communication protocol conforming to the IEEE 802.11 Standard oranother suitable wireless communication protocol. For example, the MACprocessor 126 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 130 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. Forinstance, the MAC processor 126 is configured to generate MAC layer dataunits such as MAC service data units (MSDUs), MAC protocol data units(MPDUs), etc., and provide the MAC layer data units to the PHY processor130. Additionally, the MAC processor 126 is configured to selectcommunication links via which MAC layer data units should be transmittedand to control the PHY processor 130 so that the MAC layer data unitsare transmitted in the selected communication links, in someembodiments. Also, the MAC processor 126 is configured to determine whenthe respective communication links are idle and available fortransmission and to control the PHY processor 130 so that MAC layer dataunits are transmitted when respective communication links are idle, insome embodiments. Additionally, the MAC processor 126 is configured todetermine when client stations are in a sleep state and thereforeunavailable to transmit or receive, in some embodiments. For example,the MAC processor 126 is configured to negotiate a schedule with aclient station for when the client station is permitted to be in thesleep state and when the client station should be in a wake state andavailable to transmit to or receive from the AP 114, according to someembodiments.

The PHY processor 130 may be configured to receive MAC layer data unitsfrom the MAC processor 126 and to encapsulate the MAC layer data unitsto generate PHY data units such as PHY protocol data units (PPDUs) fortransmission via the antennas 138. Similarly, the PHY processor 130 maybe configured to receive PHY data units that were received via theantennas 138, and to extract MAC layer data units encapsulated withinthe PHY data units. The PHY processor 130 may provide the extracted MAClayer data units to the MAC processor 126, which processes the MAC layerdata units.

PHY data units are sometimes referred to herein as “packets”, and MAClayer data units are sometimes referred to herein as “frames”.

In connection with generating one or more RF signals for transmission,the PHY processor 130 is configured to process (which may includemodulation, filtering, etc.) data corresponding to a PPDU to generateone or more digital baseband signals, and convert the digital basebandsignal(s) to one or more analog baseband signals, according to anembodiment. Additionally, the PHY processor 130 is configured toupconvert the one or more analog baseband signals to one or more RFsignals for transmission via the one or more antennas 138.

In connection with receiving one or more RF signals, the PHY processor130 is configured to downconvert the one or more RF signals to one ormore analog baseband signals, and to convert the one or more analogbaseband signals to one or more digital baseband signals. The PHYprocessor 130 is further configured to process (which may includedemodulation, filtering, etc.) the one or more digital baseband signalsto generate a PPDU.

The PHY processor 130 includes amplifiers (e.g., a low noise amplifier(LNA), a power amplifier, etc.), an RF downconverter, an RF upconverter,a plurality of filters, one or more analog-to-digital converters (ADCs),one or more digital-to-analog converters (DACs), one or more discreteFourier transform (DFT) calculators (e.g., a fast Fourier transform(FFT) calculator), one or more inverse discrete Fourier transform (IDFT)calculators (e.g., an inverse fast Fourier transform (IFFT) calculator),one or more modulators, one or more demodulators, etc., in variousembodiments.

The PHY processor 130 is configured to generate one or more RF signalsthat are provided to the one or more antennas 138. The PHY processor 130is also configured to receive one or more RF signals from the one ormore antennas 138.

The MAC processor 126 is configured to control the PHY processor 130 togenerate one or more RF signals, for example, by providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 130, andoptionally providing one or more control signals to the PHY processor130, according to some embodiments. In an embodiment, the MAC processor126 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a readROM, a flash memory, etc. In other embodiments, the MAC processor 126additionally or alternatively includes one or more hardware statemachines.

The PHY processor 130 includes, or implements, a spatial configurationsubfield generator 142 that is configured to generate spatialconfiguration subfields suitable for indicating spatial streamallocations for one or more MU-MIMO transmissions within a DL MU packetof up to sixteen spatial streams to up to eight client stations,according to some embodiments. When the AP 114 is to transmit a DL MUpacket that utilizes MU-MIMO, the spatial configuration subfieldgenerator 142 generates, for each client station that is an intendedreceiver of an MU-MIMO transmission within the DL MU packet, a spatialconfiguration subfield that indicates how many spatial stream(s) in theDL MU packet correspond to the client station, according to anembodiment. The spatial configuration subfields generated by the spatialconfiguration subfield generator 142 are included in a PHY preamble ofthe DL MU packet.

In an embodiment, the spatial configuration subfield generator 142comprises hardware circuitry that is configured to generate spatialconfiguration subfields having encodings such as described below. Inanother embodiment, the spatial configuration subfield generator 142 isimplemented by a processor executing machine readable instructionsstored in a memory, where the machine readable instructions cause theprocessor to generate spatial configuration subfields having encodingssuch as described below.

In another embodiment, the MAC processor 126 includes, or implements,the spatial configuration subfield generator 142.

To support transmission of up to 16 spatial streams, as being consideredfor the IEEE 802.11be Standard, the PHY processor 130 comprises hardwarecomponents (e.g., amplifiers, modulators, RF transceivers, etc.)suitable for generating and transmitting up to 16 spatial streams,according to an embodiment. As an illustrative example, the PHYprocessor 130 comprises at least eight spatial stream parsers, accordingto an embodiment. As another illustrative example, the PHY processor 130comprises four spatial stream parsers (of the at least eight spatialstream parsers) that are capable of parsing into up to four spatialstreams, according to an embodiment. As another illustrative example,the PHY processor 130 comprises no more than three spatial streamparsers (of the at least eight spatial stream parsers) that are capableof parsing into up to four spatial streams, according to an embodiment.As another illustrative example, the PHY processor 130 comprises no morethan two spatial stream parsers (of the at least eight spatial streamparsers) that are capable of parsing into up to four spatial streams,according to an embodiment. To support transmission of up to 16 spatialstreams to up to eight client stations, the MAC processor 126 comprisessuitable processing and throughput capability for providing data to thePHY processor 130 for up to eight client stations and that can be parsedby the PHY processor 130 into up to 16 spatial streams, according to anembodiment.

The WLAN 110 also includes a plurality of client stations 154. Althoughthree client stations 154 are illustrated in FIG. 1 , the WLAN 110includes other suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of clientstations 154 in various embodiments. The client station 154-1 includes ahost processor 158 coupled to a wireless network interface device 162.The wireless network interface device 162 includes one or more MACprocessors 166 (sometimes referred to herein as “the MAC processor 166”for brevity) and one or more PHY processors 170 (sometimes referred toherein as “the PHY processor 170” for brevity). The PHY processor 170includes a plurality of transceivers 174, and the transceivers 174 arecoupled to a plurality of antennas 178. Although three transceivers 174and three antennas 178 are illustrated in FIG. 1 , the client station154-1 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) oftransceivers 174 and antennas 178 in other embodiments. In someembodiments, the client station 154-1 includes a higher number ofantennas 178 than transceivers 174, and antenna switching techniques areutilized.

In an embodiment, the wireless network interface device 162 isconfigured for operation within a single RF band at a given time. Inanother embodiment, the wireless network interface device 162 isconfigured for operation within two or more RF bands at the same time orat different times. For example, in an embodiment, the wireless networkinterface device 162 includes multiple PHY processors 170, whererespective PHY processors 170 correspond to respective RF bands. Inanother embodiment, the wireless network interface device 162 includes asingle PHY processor 170, where each transceiver 174 includes respectiveRF radios corresponding to respective RF bands. In an embodiment, thewireless network interface device 162 includes multiple MAC processors166, where respective MAC processors 166 correspond to respective RFbands. In another embodiment, the wireless network interface device 162includes a single MAC processor 166 corresponding to the multiple RFbands.

The wireless network interface device 162 is implemented using one ormore ICs configured to operate as discussed below. For example, the MACprocessor 166 may be implemented on at least a first IC, and the PHYprocessor 170 may be implemented on at least a second IC. The first ICand the second IC may be packaged together in a single IC packagethereby forming a modular device, or the first IC and the second IC maybe coupled together on a single PCB, for example, or another suitablesubstrate, in various embodiments. As another example, at least aportion of the MAC processor 166 and at least a portion of the PHYprocessor 170 may be implemented on a single IC. For instance, thewireless network interface device 162 may be implemented using an SoC,where the SoC includes at least a portion of the MAC processor 166 andat least a portion of the PHY processor 170.

In an embodiment, the host processor 158 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, thehost processor 158 may be implemented, at least partially, on a firstIC, and the network device 162 may be implemented, at least partially,on a second IC. As another example, the host processor 158 and at leasta portion of the wireless network interface device 162 may beimplemented on a single IC.

In various embodiments, the MAC processor 166 and the PHY processor 170of the client station 154-1 are configured to generate data units, andprocess received data units, that conform to the WLAN communicationprotocol or another suitable communication protocol. For example, theMAC processor 166 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 170 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. The MACprocessor 166 may be configured to generate MAC layer data units such asMSDUs, MPDUs, etc., and provide the MAC layer data units to the PHYprocessor 170. Additionally, the MAC processor 166 is configured toselect communication links via which MAC layer data units should betransmitted and to control the PHY processor 170 so that the MAC layerdata units are transmitted in the selected communication links, in someembodiments. Also, the MAC processor 166 is configured to determine whenthe respective communication links are idle and available fortransmission and to control the PHY processor 170 so that MAC layer dataunits are transmitted when respective communication links are idle, insome embodiments. Additionally, the MAC processor 166 is configured tocontrol when portions of the wireless network interface device 162 arein a sleep state or a wake state, for example to conserve power, in someembodiments. For example, the MAC processor 166 is configured tonegotiate a schedule with the AP 114 for when the client station 154-1is permitted to be in the sleep state and when the client station 154-1should be in a wake state and available to transmit to or receive fromthe AP 114, according to some embodiments.

The PHY processor 170 may be configured to receive MAC layer data unitsfrom the MAC processor 166 and encapsulate the MAC layer data units togenerate PHY data units such as PPDUs for transmission via the antennas178. Similarly, the PHY processor 170 may be configured to receive PHYdata units that were received via the antennas 178, and extract MAClayer data units encapsulated within the PHY data units. The PHYprocessor 170 may provide the extracted MAC layer data units to the MACprocessor 166, which processes the MAC layer data units.

The PHY processor 170 is configured to downconvert one or more RFsignals received via the one or more antennas 178 to one or morebaseband analog signals, and convert the analog baseband signal(s) toone or more digital baseband signals, according to an embodiment. ThePHY processor 170 is further configured to process the one or moredigital baseband signals to demodulate the one or more digital basebandsignals and to generate a PPDU. The PHY processor 170 includesamplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter,an RF upconverter, a plurality of filters, one or more ADCs, one or moreDACs, one or more DFT calculators (e.g., an FFT calculator), one or moreIDFT calculators (e.g., an IFFT calculator), one or more modulators, oneor more demodulators, etc.

The PHY processor 170 is configured to generate one or more RF signalsthat are provided to the one or more antennas 178. The PHY processor 170is also configured to receive one or more RF signals from the one ormore antennas 178.

The MAC processor 166 is configured to control the PHY processor 170 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 170, andoptionally providing one or more control signals to the PHY processor170, according to some embodiments. In an embodiment, the MAC processor166 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In an embodiment, the MAC processor 166 includes ahardware state machine.

The PHY processor 170 includes, or implements, a spatial configurationsubfield decoder 192 that is configured to decode a spatialconfiguration subfield that is suitable for indicating allocations forMU-MIMO transmission in a DL MU packet of up to sixteen spatial streamsto up to eight client stations, according to some embodiments. When theclient station receives a DL MU packet, the spatial configurationsubfield decoder 192 decodes the spatial configuration subfieldcorresponding to the client station to determine how many spatialstreams in the DL MU packet correspond to the client station, accordingto an embodiment.

In an embodiment, the spatial configuration subfield decoder 192comprises hardware circuitry that is configured to decode a spatialconfiguration subfield having encodings such as described below. Inanother embodiment, the spatial configuration subfield decoder 192 isimplemented by a processor executing machine readable instructionsstored in a memory, where the machine readable instructions cause theprocessor to decode spatial configuration subfields having encodingssuch as described below.

In another embodiment, the MAC processor 166 includes, or implements,the spatial configuration subfield decoder 192.

In an embodiment, each of the client stations 154-2 and 154-3 has astructure that is the same as or similar to the client station 154-1. Inan embodiment, one or more of the client stations 154-2 and 154-3 has adifferent suitable structure than the client station 154-1. Each of theclient stations 154-2 and 154-3 has the same or a different number oftransceivers and antennas. For example, the client station 154-2 and/orthe client station 154-3 each have only two transceivers and twoantennas (not shown), according to an embodiment.

FIG. 2 is a diagram of an example portion 200 (referred to herein as the“signal field 200” for ease of explanation) of a PHY preamble includedin a DL MU packet, according to an embodiment. The signal field 200includes common information 204 regarding the DL MU packet that iscommon for all intended receivers of the DL MU packet. For example, thecommon information 204 includes RU allocation information 208 thatindicates how frequency resources or frequency segments, e.g., RUs, areallocated within the DL MU packet, and how many client stations areallocated to each RU, according to an embodiment. If more than oneclient station is allocated to a single RU, this indicates to clientstations that the RU corresponds to an MU-MIMO transmission, accordingto an embodiment.

The signal field 200 also includes user specific information 212regarding the DL MU packet that is specific to individual receivers ofthe DL MU packet, according to an embodiment. For example, the userspecific information 212 includes a respective user field 216 for eachintended receiver of the DL MU packet, according to an embodiment. Eachuser field 216 includes a station identifier (STA ID) 220 that is anidentifier of a particular client station and indicates the clientstation to which the user field 216 corresponds.

Additionally, at least when the client station is an intended receiverof an MU-MIMO transmission, the user field 216 includes a spatialconfiguration subfield 224. In some embodiments, when the client stationis not an intended receiver of an MU-MIMO transmission, the user field216 does not include the spatial configuration subfield 224. As will bedescribed in more detail below, the spatial configuration subfield 224indicates how many spatial streams correspond to the client station. Insome embodiments, the spatial configuration subfield 224 consists of sixbits. In other embodiments, the spatial configuration subfield 224consists of five bits. In other embodiments, the spatial configurationsubfield 224 consists of four bits.

The user fields 216 are arranged in an order, according to anembodiment. As will be described in more detail below, when a set ofuser fields 216 corresponds to a MU-MIMO transmission, a client stationuses the order of user fields 216 to determine a position, within theset, of the user field 216 that corresponds to the client station, anduses the determined position, within the set, to decode the spatialconfiguration subfield 224, according to an embodiment.

Table 1 is an example encoding of a 6-bit spatial configuration subfieldfor an MU-MIMO transmission, according to an embodiment. The parameterNuser (Number of Users) indicates a total number of client stations thatare intended receivers of the MU-MIMO transmission. The parameterNSTS[x] (Number of Spatial Streams) indicates a number of spatialstreams allocated to an x-th client station, where x indicates aposition, within a set of user fields 216 corresponding to the MU-MIMOtransmission, of a user field 216 that corresponds to a client station.

In the example encoding of Table 1, a maximum total number of clientstations corresponding to a single MU-MIMO transmission is eight, i.e.,Nuser≤8. In other embodiments, a maximum total number of client stationscorresponding to a single MU-MIMO transmission is a suitable number morethan eight, such as nine, ten, eleven, etc. Additionally, in the exampleencoding of Table 1, a client station can be allocated a maximum of fourspatial streams, i.e., NSTS≤4. In other embodiments, a client stationcan be allocated a suitable number of spatial streams that is more thanfour.

Additionally, in the example encoding of Table 1, NSTS assigned toclient stations are in the descending order according to the order ofuser fields 216. For example, NSTS[m] is greater than or equal toNSTS[m+1], according to an embodiment.

TABLE 1 Spatial Config. Subfield (bits NSTS NSTS NSTS NSTS NSTS NSTSNSTS NSTS Total Number Nuser B5-B0) [1] [2] [3] [4] [5] [6] [7] [8] NSTSof entries 2 000000- 1-4 1 2-5 10 000011 000100- 2-4 2 4-6 000110000111- 3-4 3 6-7 001000 001001 4 4  8 3 000000- 1-4 1 1 3-6 20 000011000100- 2-4 2 1 5-7 000110 000111- 3-4 3 1 7-8 001000 001001 4 4 1  9001010- 2-4 2 2 6-8 001100 001101- 3-4 3 2 8-9 001110 001111 4 4 2 10010000- 3-4 3 3  9-10 010001 010010 4 4 3 11 010011 4 4 4 12 4 000000-1-4 1 1 1 4-7 34 000011 000100- 2-4 2 1 1 6-8 000110 000111- 3-4 3 1 18-9 001000 001001 4 4 1 1 10 001010- 2-4 2 2 1 7-9 001100 001101- 3-4 32 1  9-10 001110 001111 4 4 2 1 11 010000- 3-4 3 3 1 10-11 010001 0100104 4 3 1 12 010011 4 4 4 1 13 010100- 2-4 2 2 2  8-10 010110 010111- 3-43 2 2 10-11 011000 011001 4 4 2 2 12 011010- 3-4 3 3 2 11-12 011011011100 4 4 3 2 13 011101 4 4 4 2 14 011110- 3-4 3 3 3 12-13 011111100000 4 4 4 3 15 100001 4 4 4 4 16 5 000000- 1-4 1 1 1 1 5-8 49 000011000100- 2-4 2 1 1 1 7-9 000110 000111- 3-4 3 1 1 1  9-10 001000 001001 44 1 1 1 11 001010- 2-4 2 2 1 1  8-10 001100 001101- 3-4 3 2 1 1 10-11001110 001111 4 4 2 1 1 12 010000- 3-4 3 3 1 1 11-12 010001 010010 4 4 31 1 13 010011 4 4 4 1 1 14 010100- 2-4 2 2 2 1  9-11 010110 010111- 3-43 2 2 1 11-12 011000 011001 4 4 2 2 1 13 011010- 3-4 3 3 2 1 12-13011011 011100 4 4 3 2 1 14 011101 4 4 4 2 1 15 011110- 3-4 3 3 3 1 13-14011111 100000 4 4 3 3 1 15 100001 4 4 4 3 1 16 100010- 2-4 2 2 2 2 10-12100100 100101- 3-4 3 2 2 2 12-13 100110 100111 4 4 2 2 2 14 101000- 3-43 3 2 2 13-14 101001 101010 4 4 3 2 2 15 101011 4 4 4 2 2 16 101100- 3-43 3 3 2 14-15 101101 101110 4 4 3 3 2 16 101111- 3-4 3 3 3 3 15-16110000 6 000000- 1-4 1 1 1 1 1 6-9 54 000011 000100- 2-4 2 1 1 1 1  8-10000110 000111- 3-4 3 1 1 1 1 10-11 001000 001001 4 4 1 1 1 1 12 001010-2-4 2 2 1 1 1  9-11 001100 001101- 3-4 3 2 1 1 1 11-12 001110 001111 4 42 1 1 1 13 010000- 3-4 3 3 1 1 1 12-13 010001 010010 4 4 3 1 1 1 14010011 4 4 4 1 1 1 15 010100- 2-4 2 2 2 1 1 10-12 010110 010111- 3-4 3 22 1 1 12-13 011000 011001 4 4 2 2 1 1 14 011010- 3-4 3 3 2 1 1 13-14011011 011100 4 4 3 2 1 1 15 011101 4 4 4 2 1 1 16 011110- 3-4 3 3 3 1 114-15 011111 100000 4 4 3 3 1 1 16 100001- 2-4 2 2 2 2 1 11-13 100011100100- 3-4 3 2 2 2 1 13-14 100101 100110 4 4 2 2 2 1 15 100111- 3-4 3 32 2 1 14-15 101000 101001 4 4 3 2 2 1 16 101010- 3-4 3 3 3 2 1 15-16101011 101100 3 3 3 3 3 1 16 101101- 2-4 2 2 2 2 2 12-14 101111 110000-3-4 3 2 2 2 2 14-15 110001 110010 4 4 2 2 2 2 16 110011- 3-4 3 3 2 2 215-16 110100 110101 3 3 3 3 2 2 16 7 000000- 1-4 1 1 1 1 1 1  7-10 50000011 000100- 2-4 2 1 1 1 1 1  9-11 000110 000111- 3-4 3 1 1 1 1 111-12 001000 001001 4 4 1 1 1 1 1 13 001010- 2-4 2 2 1 1 1 1 10-12001100 001101- 3-4 3 2 1 1 1 1 12-13 001110 001111 4 4 2 1 1 1 1 14010000- 3-4 3 3 1 1 1 1 13-14 010001 010010 4 4 3 1 1 1 1 15 010011 4 44 1 1 1 1 16 010100- 2-4 2 2 2 1 1 1 11-13 010110 010111- 3-4 3 2 2 1 11 13-14 011000 011001 4 4 2 2 1 1 1 15 011010- 3-4 3 3 2 1 1 1 14-15011011 011100 4 4 3 2 1 1 1 16 011101- 3-4 3 3 3 1 1 1 15-16 011110011111- 2-4 2 2 2 2 1 1 12-14 100001 100010- 3-4 3 2 2 2 1 1 14-15100011 100100 4 4 2 2 2 1 1 16 100101- 3-4 3 3 2 2 1 1 15-16 100110100111 3 3 3 3 2 1 1 16 101000- 2-4 2 2 2 2 2 1 13-15 101010 101011- 3-43 2 2 2 2 1 15-16 101100 101101 3 3 3 2 2 2 1 16 101110- 2-4 2 2 2 2 2 214-16 110000 110001 3 3 2 2 2 2 2 16 8 000000- 1-4 1 1 1 1 1 1 1  8-1141 000011 000100- 2-4 2 1 1 1 1 1 1 10-12 000110 000111- 3-4 3 1 1 1 1 11 12-13 001000 001001 4 4 1 1 1 1 1 1 14 001010- 2-4 2 2 1 1 1 1 1 11-13001100 001101- 3-4 3 2 1 1 1 1 1 13-14 001110 001111 4 4 2 1 1 1 1 1 15010000- 3-4 3 3 1 1 1 1 1 14-15 010001 010010 4 4 3 1 1 1 1 1 16 010011-2-4 2 2 2 1 1 1 1 12-14 010101 010110- 3-4 3 2 2 1 1 1 1 14-15 010111011000 4 4 2 2 1 1 1 1 16 011001- 3-4 3 3 2 1 1 1 1 15-16 011010 0110113 3 3 3 1 1 1 1 16 011100- 2-4 2 2 2 2 1 1 1 13-15 011110 011111- 3-4 32 2 2 1 1 1 15-16 100000 100001 3 3 3 2 2 1 1 1 16 100010- 2-4 2 2 2 2 21 1 14-16 100100 100101 3 3 2 2 2 2 1 1 16 100110- 2-3 2 2 2 2 2 2 115-16 100111 101000 2 2 2 2 2 2 2 2 16

The example encoding of Table 1 accommodates all possible permutationsof MU-MIMO spatial stream allocations, subject to the restrictionsdiscussed above. Because a spatial configuration subfield 224 isincluded in each user field 216 corresponding to a MU-MIMO transmission,the overhead associated with the spatial configuration subfield 224 canbe significant, especially for wide bandwidth DL MU packets such as 160MHz or 320 MHz, which can accommodate larger numbers of RUs, each ofwhich may be used for an MU-MIMO transmission.

Some of the MU-MIMO configurations listed in Table 1 are inferior tosome other MU-MIMO pairings listed in Table 1, e.g., less throughputwith the same or even greater total number of spatial streams, and/orrequire higher transmit power to achieve the same throughput. Byremoving some of the possible MU-MIMO configurations, such as inferiorMU-MIMO configurations, the total number of MU-MIMO configurations canbe reduced and thus the number of bits used for the spatialconfiguration subfields 224 can be reduced.

Table 2 is an example encoding of a 5-bit spatial configuration subfieldfor an MU-MIMO transmission, according to another embodiment. Similar tothe example encoding of Table 1, a maximum total number of clientstations corresponding to a single MU-MIMO transmission is eight, i.e.,Nuser≤8, and a client station can be allocated a maximum of four spatialstreams, i.e., NSTS≤4. In other embodiments, a maximum total number ofclient stations corresponding to a single MU-MIMO transmission is asuitable number more than eight, such as nine, ten, eleven, etc., and/ora client station can be allocated a suitable number of spatial streamsthat is more than four. Additionally, similar to the example encoding ofTable 1, NSTS assigned to client stations are in the descending orderaccording to the order of user fields 216. For example, NSTS[m] isgreater than or equal to NSTS[m+1], according to an embodiment.

TABLE 2 Spatial Config. Subfield (bits NSTS NSTS NSTS NSTS NSTS NSTSNSTS NSTS Total Number Nuser B4-B0) [1] [2] [3] [4] [5] [6] [7] [8] NSTSof entries 2 00000- 1-4 1 2-5 10 00011 00100- 2-4 2 4-6 00110 00111- 3-43 6-7 01000 01001 4 4  8 3 00000- 1-4 1 1 3-6 20 00011 00100- 2-4 2 15-7 00110 00111- 3-4 3 1 7-8 01000 01001 4 4 1  9 01010- 2-4 2 2 6-801100 01101- 3-4 3 2 8-9 01110 01111 4 4 2 10 10000- 3-4 3 3  9-10 1000110010 4 4 3 11 10011 4 4 4 12 4 00000- 1-4 1 1 1 4-7 32 00011 00100- 2-42 1 1 6-8 00110 00111- 3-4 3 1 1 8-9 01000 01001 4 4 1 1 10 01010- 2-4 22 1 7-9 01100 01101- 3-4 3 2 1  9-10 01110 01111 4 4 2 1 11 10000- 3-4 33 1 10-11 10001 10010 4 4 3 1 12 10011 4 4 4 1 13 10100- 2-4 2 2 2  8-1010110 10111- 3-4 3 2 2 10-11 11000 11001 4 4 2 2 12 11010- 3-4 3 3 211-12 11011 11100 4 4 3 2 13 11101 4 4 4 2 14 11110- 3-4 3 3 3 12-1311111 5 00000- 1-4 1 1 1 1 5-8 32 00011 00100- 2-4 2 1 1 1 7-9 0011000111- 3-4 3 1 1 1  9-10 01000 01001 4 4 1 1 1 11 01010- 2-4 2 2 1 1 8-10 01100 01101- 3-4 3 2 1 1 10-11 01110 10000 3 3 3 1 1 11 10001- 2-42 2 2 1  9-11 10010 10011- 3-4 3 2 2 1 11-12 10100 10101- 3-4 3 3 2 112-13 10110 10111 3 3 3 3 1 13 11000- 2-4 2 2 2 2 10-12 11010 11011- 3-43 2 2 2 12-13 11100 11101- 3-4 3 3 2 2 13-14 11110 11111 3 3 3 3 2 14 600000- 1-4 1 1 1 1 1 6-9 32 00011 00100- 2-4 2 1 1 1 1  8-10 0011000111- 3-4 3 1 1 1 1 10-11 01000 01001- 2-4 2 2 1 1 1  9-11 01011 01100-3-4 3 2 1 1 1 11-12 01101 01110- 3-4 3 3 1 1 1 12-13 01111 10000- 2-4 22 2 1 1 10-12 10010 10011- 3-4 3 2 2 1 1 12-13 10100 10101 3 3 3 2 1 113 10110- 2-4 2 2 2 2 1 11-13 11000 11001- 3-4 3 2 2 2 1 13-14 1101011011 3 3 3 2 2 1 14 11100- 2-4 2 2 2 2 2 12-14 11110 11111 3 3 2 2 2 214 7 00000- 1-4 1 1 1 1 1 1  7-10 32 00011 00100- 2-4 2 1 1 1 1 1  9-1100110 00111 3 3 1 1 1 1 1 11 01000- 2-4 2 2 1 1 1 1 10-12 01010 01011 33 2 1 1 1 1 12 01100 3 3 3 1 1 1 1 13 01101- 2-4 2 2 2 1 1 1 11-13 0111110000 3 3 2 2 1 1 1 13 10001 3 3 3 2 1 1 1 14 10010 3 3 3 3 1 1 1 1510011- 2-4 2 2 2 2 1 1 12-14 10101 10110 3 3 2 2 2 1 1 14 10111 3 3 3 32 1 1 16 11000- 2-4 2 2 2 2 2 1 13-15 11010 11011 3 3 2 2 2 2 1 15 111003 3 3 2 2 2 1 16 11101- 2-3 2 2 2 2 2 2 14-15 11110 11111 3 3 2 2 2 2 216 8 00000- 1-4 1 1 1 1 1 1 1  8-11 32 00011 00100- 2-4 2 1 1 1 1 1 110-12 00110 00111- 3-4 3 1 1 1 1 1 1 12-13 01000 01001- 2-4 2 2 1 1 1 11 11-13 01011 01100 3 3 2 1 1 1 1 1 13 01101 3 3 3 1 1 1 1 1 14 01110-2-4 2 2 2 1 1 1 1 12-14 10000 10001 3 3 2 2 1 1 1 1 14 10010 3 3 3 2 1 11 1 15 10011 3 3 3 3 1 1 1 1 16 10100- 2-4 2 2 2 2 1 1 1 13-15 1011010111 3 3 2 2 2 1 1 1 15 11000 3 3 3 2 2 1 1 1 16 11001- 2-4 2 2 2 2 2 11 14-16 11011 11100 3 3 2 2 2 2 1 1 16 11101- 2-3 2 2 2 2 2 2 1 15-1611110 11111 2 2 2 2 2 2 2 2 16

In the example encoding of Table 2, for Nuser=4, when three clientstations are each allocated four spatial streams, the total number ofspatial streams cannot exceed 14. Also, for Nuser=5, no more than twoclient stations can be allocated four spatial streams; and when twoclient stations are allocated four spatial streams, the total number ofstreams cannot exceed 11. For Nuser≥6, no more than one client stationcan be allocated four spatial streams. For Nuser≤6, the total number ofspatial streams cannot exceed fourteen. For Nuser=7, when one clientstation is allocated four spatial streams, no other client station canbe allocated more than two spatial streams. For Nuser=8, when one clientstation is allocated four spatial streams and another client station isallocated three spatial streams, the total number of spatial streamscannot exceed thirteen.

Table 3 is an example encoding of a 4-bit spatial configuration subfieldfor an MU-MIMO transmission, according to another embodiment. Similarlyto the example encoding of Table 1, a maximum total number of clientstations corresponding to a single MU-MIMO transmission is eight, i.e.,Nuser≤8, and a client station can be allocated a maximum of four spatialstreams, i.e., NSTS≤4. In other embodiments, a maximum total number ofclient stations corresponding to a single MU-MIMO transmission is asuitable number more than eight, such as nine, ten, eleven, etc., and/ora client station can be allocated a suitable number of spatial streamsthat is more than four. Additionally, similarly to the example encodingof Table 1, NSTS assigned to client stations are in the descending orderaccording to the order of user fields 216. For example, NSTS[m] isgreater than or equal to NSTS[m+1], according to an embodiment.

TABLE 3 Spatial Config. Subfield (bits NSTS NSTS NSTS NSTS NSTS NSTSNSTS NSTS Total Number Nuser B3-B0) [1] [2] [3] [4] [5] [6] [7] [8] NSTSof entries 2 0000- 1-4 1 2-5 10 0011 0100- 2-4 2 4-6 0110 0111- 3-4 36-7 1000 1001 4 4  8 3 0000- 1-4 1 1 3-6 16 0011 0100- 2-4 2 1 5-7 01100111- 3-4 3 1 7-8 1000 1001- 2-4 2 2 6-8 1011 1100- 3-4 3 2 8-9 11011110- 3-4 3 3  9-10 1111 4 0000- 1-4 1 1 1 4-7 16 0011 0100- 2-4 2 1 16-8 0110 0111 3 3 1 1  8 1000- 2-4 2 2 1 7-9 1010 1011 3 3 2 1  9 1100-2-4 2 2 2  8-10 1110 1111 3 3 2 2 10 5 0000- 1-4 1 1 1 1 5-8 16 00110100- 2-4 2 1 1 1 7-9 0110 0111 3 3 1 1 1  9 1000- 2-3 2 2 1 1 8-9 10011010 3 3 2 1 1 10 1011- 2-3 2 2 2 1  9-10 1100 1101 3 3 2 2 1 11 1110-2-3 2 2 2 2 10-11 1111 6 0000- 1-4 1 1 1 1 1 6-9 16 0011 0100- 2-3 2 1 11 1 8-9 0101 0110 3 3 1 1 1 1 10 0111- 2-3 2 2 1 1 1  9-10 1000 1001 3 32 1 1 1 11 1010- 2-3 2 2 2 1 1 10-11 1011 1100- 2-3 2 2 2 2 1 11-12 11011110- 2-3 2 2 2 2 2 12-13 1111 7 0000- 1-4 1 1 1 1 1 1  7-10 16 00110100- 2-3 2 1 1 1 1 1  9-10 0101 0110 3 3 1 1 1 1 1 11 0111- 2-3 2 2 1 11 1 10-11 1000 1001- 2-3 2 2 2 1 1 1 11-12 1010 1011 3 3 2 2 1 1 1 131100- 2-3 2 2 2 2 1 1 12-13 1101 1110- 2-3 2 2 2 2 2 1 13-14 1111 80000- 1-4 1 1 1 1 1 1 1  8-11 16 0011 0100- 2-3 2 1 1 1 1 1 1 10-11 01010110- 2-3 2 2 1 1 1 1 1 11-12 0111 1000- 2-3 2 2 2 1 1 1 1 12-13 10011010- 2-3 2 2 2 2 1 1 1 13-14 1011 1100- 2-3 2 2 2 2 2 1 1 14-15 11011110 2 2 2 2 2 2 2 1 15 1111 2 2 2 2 2 2 2 2 16

In the example encoding of Table 3, for Nuser≥3, no more than one clientstation can be allocated four spatial streams. For Nuser=3 or 4, thetotal number of spatial streams cannot exceed ten. For Nuser≥4, if oneclient station is allocated three spatial streams, no other clientstation can be allocated more than three spatial streams. For Nuser≥5,two client stations are allocated two spatial streams, no other clientstation can be allocated more than three spatial streams. For Nuser=5,the total number of spatial streams cannot exceed eleven. For Nuser≥6,if two client stations are allocated two spatial streams, no otherclient station can be allocated more than three spatial streams. ForNuser=6, the total number of spatial streams cannot exceed 13. ForNuser=7, the total number of spatial streams cannot exceed 14.

Referring now to FIGS. 1 and 2 , and Tables 1-3, in connection withdecoding a spatial stream configuration subfield of an MU PHY packet,the spatial stream configuration decoder 192 receives i) a number ofintended receivers for an MU-MIMO transmission within the MU PHY packet,and ii) an indication of a position, within a set of user fields 216corresponding to the MU-MIMO transmission, of the user field 216 thatcorresponds to the client station, and uses the determined position,within the set, to decode the spatial configuration subfield 224,according to an embodiment. For example, the number of intendedreceivers and the value of the spatial stream configuration subfieldindicate a particular row of the Tables 1-3, and the position of theuser field 216 indicates a particular column of the Tables 1-3. Theindicated row and column of the Tables 1-3 indicate a particular numberof spatial streams corresponding to the client station 154.

In an embodiment, the client station determines the number of intendedreceivers for the MU-MIMO transmission within the MU PHY packet usinginformation in the RU allocation information 208. In an embodiment, theclient station determines the position, within the set of user fields216 corresponding to the MU-MIMO transmission, of the user field 216that corresponds to the client station by analyzing the RU allocationinformation 208 and the user fields 216.

FIG. 3 is a flow diagram of an example method 300 for communicating in aWLAN that utilizes MU-MIMO, according to an embodiment. In someembodiments, the AP 114 is configured to implement the method 300, andFIG. 3 is described with reference to FIG. 1 merely for explanatorypurposes. In other embodiments, the method 300 is implemented by anothersuitable communication device.

At block 304, a first communication device determines (e.g., the networkinterface 122 determines, the MAC processor 126 determines, etc.) anallocation of spatial streams for a plurality of second communicationdevices that are intended receivers of an MU-MIMO transmission by thefirst communication device. In an embodiment, the first communication isconfigured to (e.g., the network interface 122 is configured to, the MACprocessor 126 is configured to, etc.) allocate up to sixteen spatialstreams to up to eight intended receivers.

At block 308, the first communication device generates (e.g., thenetwork interface 122 generates, the PHY processor 130 generates, thespatial stream configuration subfield generator 142 generates, etc.) asubfield that indicates respective numbers of spatial streams allocatedto respective second communication devices among the plurality of secondcommunication devices. In an embodiment, generating the subfield atblock 308 is performed according to an encoding that supports allocatingup to sixteen spatial streams to up to eight intended receivers. In anembodiment, the subfield is generated at block 308 to consist of six orfewer bits.

In one embodiment, generating the subfield at block 308 comprisesgenerating the subfield according to the encoding of Table 1. In anotherembodiment, generating the subfield at block 308 comprises generatingthe subfield according to the encoding of Table 2. In anotherembodiment, generating the subfield at block 308 comprises generatingthe subfield according to the encoding of Table 3.

In an embodiment, generating the subfield at block 308 comprisesgenerating the subfield according to an encoding that supports only asubset of all possible combinations of i) numbers of spatial streams toup to sixteen, and ii) numbers of intended receivers up to eight; anddetermining the allocation of spatial streams at block 304 comprisesdetermining an allocation of spatial streams from the subset.

In another embodiment, generating the subfield at block 308 comprisesgenerating the subfield to consist of five bits.

In another embodiment, generating the subfield at block 308 comprisesgenerating the subfield according to an encoding that supports only asubset of all possible combinations that excludes allocating fourspatial streams to three or more intended receivers when the number ofintended receivers is five or more.

In another embodiment, generating the subfield at block 308 comprisesgenerating the subfield according to an encoding that supports only asubset of all possible combinations that excludes allocating fourspatial streams to more than one intended receiver when the number ofintended receivers is six or more.

In another embodiment, generating the subfield at block 308 comprisesgenerating the subfield according to an encoding that supports only asubset of all possible combinations that excludes allocating more thanfourteen spatial streams when the number of intended receivers is lessthan seven.

In another embodiment, generating the subfield at block 308 comprisesgenerating the subfield to consist of four bits.

In another embodiment, generating the subfield at block 308 comprisesgenerating the subfield according to an encoding that supports only asubset of all possible combinations that excludes allocating fourspatial streams to two or more intended receivers when the number ofintended receivers is three or more.

In another embodiment, generating the subfield at block 308 comprisesgenerating the subfield according to an encoding that supports only asubset of all possible combinations that excludes allocating more thaneleven spatial streams when the number of intended receivers if five.

At block 312, the first communication device generates (e.g., thenetwork interface 122 generates, the PHY processor 130 generates, etc.)an MU PHY data unit that includes i) a PHY preamble, and ii) the MU-MIMOtransmission. In an embodiment, generating the MU PHY data unit at block312 includes: generating the PHY preamble to include the subfield, andgenerating a PHY data portion of the MU PHY data unit to include theMU-MIMO transmission.

At block 316, the first communication device transmits (e.g., thenetwork interface 122 transmits, the PHY processor 130 transmits, thetransceivers 134 transmit, etc.) the MU PHY data unit generated at block312. In an embodiment, the MAC processor 126 controls the networkinterface 122 to transmit the MU PHY data unit.

FIG. 4 is a flow diagram of another example method 400 for communicatingin a WLAN that utilizes MU-MIMO, according to another embodiment. Insome embodiments, the client station 154-1 is configured to implementthe method 400, and FIG. 4 is described with reference to FIG. 1 merelyfor explanatory purposes. In other embodiments, the method 400 isimplemented by another suitable communication device.

At block 404, a communication device receives (e.g., the networkinterface 162 receives, the PHY processor 170 receives, the transceivers134 receive, etc.) an MU PHY data unit.

At block 408, the communication device decodes (e.g., the networkinterface 162 decodes, the PHY processor 170 decodes, the spatial streamconfiguration subfield decoder 192, etc.) a subfield (e.g., a spatialstream configuration subfield) in a PHY preamble of the MU PHY data unitreceived at block 404 to determine a number of spatial streams allocatedto the communication device in connection with the MU PHY data unit. Thesubfield indicates respective numbers of spatial streams allocated torespective second communication devices among a plurality of secondcommunication devices. In an embodiment, the subfield decoded at block408 has been encoded according to an encoding that supports allocatingup to sixteen spatial streams to up to eight intended receivers.

In an embodiment, the subfield is decoded at block 408 consists of sixor fewer bits.

In one embodiment, the subfield decoded at block 408 has been encodedaccording to the encoding of Table 1. In another embodiment, thesubfield decoded at block 408 has been encoded according to the encodingof Table 2. In another embodiment, the subfield decoded at block 408 hasbeen encoded according to the encoding of Table 3.

In an embodiment, the subfield decoded at block 408 has been encodedaccording to an encoding that supports only a subset of all possiblecombinations of i) numbers of spatial streams to up to sixteen, and ii)numbers of intended receivers up to eight.

In another embodiment, the subfield decoded at block 408 consists offive bits.

In another embodiment, the subfield decoded at block 408 has beenencoded according to an encoding that supports only a subset of allpossible combinations that excludes allocating four spatial streams tothree or more intended receivers when the number of intended receiversis five or more.

In another embodiment, the subfield decoded at block 408 has beenencoded according to an encoding that supports only a subset of allpossible combinations that excludes allocating four spatial streams tomore than one intended receiver when the number of intended receivers issix or more.

In another embodiment, the subfield decoded at block 408 has beenencoded according to an encoding that supports only a subset of allpossible combinations that excludes allocating more than fourteenspatial streams when the number of intended receivers is less thanseven.

In another embodiment, the subfield decoded at block 408 consists offour bits.

In another embodiment, the subfield decoded at block 408 has beenencoded according to an encoding that supports only a subset of allpossible combinations that excludes allocating four spatial streams totwo or more intended receivers when the number of intended receivers isthree or more.

In another embodiment, the subfield decoded at block 408 has beenencoded according to an encoding that supports only a subset of allpossible combinations that excludes allocating more than eleven spatialstreams when the number of intended receivers if five.

At block 412, the communication device processes the number of spatialstreams in the MU PHY data unit determined at block 408.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any suitable computer readablememory such as a random access memory (RAM), a read only memory (ROM), aflash memory, etc. The software or firmware instructions may includemachine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for communicating in a wireless localarea network (WLAN) that utilizes multi-user multiple input, multipleoutput (MU-MIMO), the method comprising: receiving, at a first clientstation, a multi-user physical layer (PHY) data unit from an accesspoint, the multi-user PHY data unit including i) a PHY preamble, and ii)an MU-MIMO transmission, wherein the PHY preamble includes a subfieldthat indicates respective numbers of spatial streams allocated torespective client stations among a plurality of client stations thatincludes the first client station, wherein the subfield has been encodedaccording to an encoding that supports allocating up to sixteen spatialstreams to up to eight intended receivers, wherein the encodingcorresponds to a table having table elements that indicate respectiveallocated numbers of spatial streams, wherein respective values of thesubfield correspond to respective rows of the table, and whereinrespective columns of the table correspond to the respective clientstations, and wherein the subfield is generated to consist of six orfewer bits; decoding, at the first client station, the subfield todetermine a number of spatial streams allocated to the first clientstation; and processing, by the first client station, the determinednumber of spatial streams in the MU-MIMO transmission.
 2. The method ofclaim 1, wherein the subfield consists of six bits.
 3. The method ofclaim 1, wherein: the subfield has been encoded according to an encodingthat supports only a subset of all possible combinations of i) numbersof spatial streams up to sixteen, and ii) numbers of intended receiversup to eight; and the determined number of spatial streams is from thesubset.
 4. The method of claim 3, wherein: the subfield consists of fivebits.
 5. The method of claim 4, wherein: the subfield has been encodedaccording to an encoding that supports only a subset of all possiblecombinations that excludes allocating four spatial streams to three ormore intended receivers when the number of intended receivers is five ormore.
 6. The method of claim 4, wherein: the subfield has been encodedaccording to an encoding that supports only a subset of all possiblecombinations that excludes allocating four spatial streams to more thanone intended receiver when the number of intended receivers is six ormore.
 7. The method of claim 4, wherein: the subfield has been encodedaccording to an encoding that supports only a subset of all possiblecombinations that excludes allocating more than fourteen spatial streamswhen the number of intended receivers is less than seven.
 8. The methodof claim 3, wherein: the subfield consists of four bits.
 9. The methodof claim 8, wherein: the subfield has been encoded according to anencoding that supports only a subset of all possible combinations thatexcludes allocating four spatial streams to two or more intendedreceivers when the number of intended receivers is three or more. 10.The method of claim 1, wherein: the PHY preamble includes a plurality ofuser fields arranged in an order; respective user fields in the PHYpreamble correspond to respective client stations; the subfield isincluded in a user field corresponding to the first client station; andthe respective columns of the table correspond to respective positionsof user fields within the PHY preamble.
 11. A first client station,comprising: a wireless network interface device that is configured tocommunicate in a wireless local area network (WLAN) using multi-usermultiple input, multiple output (MU-MIMO), the wireless networkinterface device having one or more integrated circuit (IC) devicesconfigured to: receive a multi-user physical layer (PHY) data unit froman access point, the multi-user PHY data unit including i) a PHYpreamble, and ii) an MU-MIMO transmission, wherein the PHY preambleincludes a subfield that indicates respective numbers of spatial streamsallocated to respective client stations among a plurality of clientstations that includes the first client station, wherein the subfieldhas been encoded according to an encoding that supports allocating up tosixteen spatial streams to up to eight intended receivers, wherein theencoding corresponds to a table having table elements that indicaterespective allocated numbers of spatial streams, wherein respectivevalues of the subfield correspond to respective rows of the table, andwherein respective columns of the table correspond to the respectiveclient stations, and wherein the subfield is generated to consist of sixor fewer bits, decode the subfield to determine a number of spatialstreams allocated to the first client station, and process thedetermined number of spatial streams in the MU-MIMO transmission. 12.The first client station of claim 11, wherein: the subfield consists ofsix bits.
 13. The first client station of claim 11, wherein: thesubfield has been encoded according to an encoding that supports only asubset of all possible combinations of i) numbers of spatial streams toup to sixteen, and ii) numbers of intended receivers up to eight; andthe determined allocation of spatial streams is from the subset.
 14. Thefirst client station of claim 13, wherein: the subfield consists of fivebits.
 15. The first client station of claim 14, wherein: the subfieldhas been encoded according to an encoding that supports only a subset ofall possible combinations that excludes allocating four spatial streamsto three or more intended receivers when the number of intendedreceivers is five or more.
 16. The first client station of claim 14,wherein: the subfield has been encoded according to an encoding thatsupports only a subset of all possible combinations that excludesallocating four spatial streams to more than one intended receiver whenthe number of intended receivers is six or more.
 17. The first clientstation of claim 14, wherein: the subfield has been encoded according toan encoding that supports only a subset of all possible combinationsthat excludes allocating more than fourteen spatial streams when thenumber of intended receivers is less than seven.
 18. The first clientstation of claim 13, wherein: the subfield consists of four bits. 19.The first client station of claim 18, wherein: the subfield has beenencoded according to an encoding that supports only a subset of allpossible combinations that excludes allocating four spatial streams totwo or more intended receivers when the number of intended receivers isthree or more.
 20. The first client station of claim 11, wherein: thePHY preamble includes a plurality of user fields arranged in an order;respective user fields in the PHY preamble correspond to respectiveclient stations; the subfield is included in a user field correspondingto the first client station; and the respective columns of the tablecorrespond to respective positions of user fields within the PHYpreamble.